The present invention relates to a sample analysis disc for use in sample analysis and a method of producing a sample analysis disc. Especially, this invention relates to a sample analysis disc for use in assay of antigens contained in a biological sample such as blood, biopolymers such as antibodies, etc., and a method of producing a sample analysis disc for use in assay.
Immunoassay for measuring antigens, antibodies, etc. contained a biological sample such as blood has been used widely for the purpose of diagnosis of disease, early diagnosis of disease in a medical checkup. Immunoassay is a method of diagnosing a disease by measuring the concentration of specific antigens (or antibodies) contained in a biological sample. The concentration measurement is performed with quantification of a result of interaction between specific antigens (or antibodies) contained in a biological sample and antibodies (or antigens) conjugated with measurable labels, that can be bound to the specific antigens (or antibodies) in specific binding.
Labels used in immunoassay exhibit high sensitivity and can be treated easily. Therefore, a variety of types of labeling have been developed, for example, RIA (Radio Immunoassay) using radioisotopes, EIA (Enzyme Immunoassay) using enzymes, FIA (Fluorescent Immunoassay) using fluorescent labels, and CLIA (Chemiluminescent Immunoassay) with chemiluminescence.
One type of EIA using enzymes, ELISA (Enzyme-Linked ImmunoSorbent Assay) is popular, especially, using a microplate. This assay is capable of simultaneous measurements of a lot of specimens by an ordinary microplate reader with a 96-well microplate at a relatively low cost. Moreover, ELISA using a microplate is advantageous over RIA using radioisotopes, for less requirements to the environment in which assay is carried out. Nevertheless, ELISA using a microplate is disadvantageous in that the preprocess for immobilizing antibodies to a plate, the antibody-antigen interaction, the B/F (Bond/Free) separation of unreacted labels by washing, the reaction of labels with enzymes, etc. require several ten minutes to several hours, resulting in several hours to about one day in the total assay process.
One tool developed in order to shorten the assay process time is a chip for assay (Lab on a chip) that is a several-centimeter square chip, having a function of assay procedure in each well of a microplate, achieved with device miniaturization technology. The chip is prepared with immobilized antibodies, a specific reagent, etc. on an assay site with ordinary ELISA preprocessing, for shortening the assay process time. Especially, the chip is equipped with a several-ten-micrometer to several-millimeter narrow flow channel that allows the antibody-antigen interaction to occur in a shorter time. Moreover, several chips can be prepared each for dedicated use in one of the assay processes to shorten the total assay process time.
Also developed is the instrument for POCT (Point of Care Test) at or near the site of patient care (in an examination room, at the bedside, etc.). The POCT instrument is useful for particular types of examination such as cardiac marker that require a long time for specimen sampling from a patient up to the result of examination at a clinical laboratory.